Unidimensional Simulation of Drying Stress in Radiata Pine Wood

Abstract

This article reports an experimental and numeric methodology for studying the development of internal stresses during drying of solid wood. For validation purposes, tests were performed for drying of radiata pine at the equivalent of constant air-drying conditions at 44°C dry-bulb and 36°C wet-bulb temperatures. The methodology involves the simulation of drying stresses caused by the development of internal moisture content gradients during drying, where the moisture content gradients are also simulated numerically based on the theory of effective diffusion coefficient. The resulting mathematical model is a second-order nonlinear set of partial differential equations with variable coefficients, which are integrated numerically through the Control Volume Finite Element Method (CVFEM). The results showed consistency between simulated values and the experimental strain and moisture content data, both in the radial and tangential directions. It was concluded that the proposed method could be a valuable tool for studying general trends in the development of stress during drying, trends which are difficult to evaluate by measuring only due to the limited amount of data points and high experimental error associated with destructive strain tests.

Keywords:

• Drying-induced stress
• Mathematical modeling
• Shrinkage
• Stress-strain
• Wood drying